Adapter for self-drilling, chemically anchorable fastening element

ABSTRACT

An adapter ( 21 ) for a self-drilling, chemically anchorable fastening element ( 11 ) is described, having a shank ( 12 ) with a first end ( 13 ) on which a drill bit head ( 16 ) is provided, and with a second, free end ( 14 ), the second end ( 14 ) of the shank ( 12 ) being provided with a threadlike outer profile ( 15 ). The adapter ( 21 ) which may be placed on the second, free end ( 14 ) of the shank ( 12 ) has an external engagement device on one end for a rotary tool receptacle of a drill which is to be used, a base section provided on the other end at a distance from the engagement means, and a hollow cylindrical connecting sleeve section which connects the base section and the engagement device. The connecting sleeve section has a threadlike inner profile which corresponds to the threadlike outer profile ( 15 ) on the shank ( 12 ). The adapter ( 21 ) is formed by a first element part ( 22 ) and a second element part ( 32 ) which are detachably connected to one another via a clutch device ( 41 ).

This claims the benefit of German Patent Application DE 10 2009 001464.0, filed Mar. 11, 2010, and hereby incorporated by reference herein.

The present invention relates to an adapter for a self-drilling,chemically anchorable fastening element.

BACKGROUND

Self-boring fastening elements, such as rock anchors and in particularchemical shear connectors, and suitable drills having rotary toolreceptacles, as well as the use thereof in mining and tunneling havebeen known to those skilled in the art for quite some time. Thesefastening elements are primarily used to stabilize walls in cavities,such as in tunnels, mine shafts, or the like. In the production ofcavities, the mechanical properties and in particular the load-bearingcapacity of the rock layers are decreased. With the aid of the fasteningelements, i.e., chemical shear connectors, these rock layers areanchored and therefore secured to undamaged rock layers located fartheraway.

The shank of the fastening elements is used on the one hand as adrilling rod, and on the other hand, in the case of a chemical shearconnector, as the receptacle for the compound to be pressed out. A drillbit head is mounted on the first end of the shank situated in thesetting direction. The second end of the shank is inserted into a rotarytool receptacle of a drill which is used to drill the fastening elementinto the substrate.

An adapter for a self-drilling, chemically anchorable fastening elementis known from DE 103 36 040 B4. The fastening element has a shank whichhas a first end with a drill bit head and a second, free end, the secondend of the shank being provided in places with a threadlike outerprofile. The adapter is situated on the second, free end of the shank,and on one end has external engagement means for a rotary toolreceptacle of a drill which is to be used, a base section provided onthe other end at a distance from the engagement means, and a hollowcylindrical connecting sleeve section which connects the base sectionand the engagement means. The connecting sleeve section has athreadlike, i.e. threaded, inner profile in places which corresponds tothe threadlike outer profile on the shank. The connecting sleeve sectionis provided with perforations for producing predetermined breakingpoints on the adapter.

The adapter is screwed onto the second, free end of the shank of thefastening element, and then the rotary tool receptacle of the drill ismounted on the engagement means designed as a quick-engagement device,for example. After the intended drilling depth is achieved, a curable,for example quick-curing, compound is applied. When the curable compoundreaches a given degree of hardness the drill is started up again, andafter a specified torque is exceeded, the predetermined breaking pointsbreak, and the portion of the adapter having the external engagementmeans, rotationally driven by the drill, is moved along the shank in thedirection of the substrate or in the direction of the drill bit head inorder to brace the fastening element anchored in the substrate.

Using the known adapter greatly simplifies the setting process for theself-drilling, chemically anchorable fastening element, thedisengagement torque being clearly definable within a certain tolerancerange.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an adapter for aself-drilling, chemically anchorable fastening element, having anarrower tolerance range for the disengagement torque.

The present invention provides an adapter for a self-drilling,chemically anchorable fastening element, having a shank with a first endon which a drill bit head is provided, and with a second, free end, thesecond end of the shank being provided, at least in places, with athreadlike outer profile, the adapter which may be placed on the second,free end of the shank having external engagement means or device on oneend for a rotary tool receptacle of a drill which is to be used, a basesection provided on the other end at a distance from the engagementmeans, and a hollow cylindrical connecting sleeve section which connectsthe base section and the engagement means, at least the connectingsleeve section having a threadlike inner profile, at least in places,which corresponds to the threadlike outer profile on the shank.

According to the present invention, the adapter is formed by a firstelement part and a second element part which are detachably connected toone another via a clutch device.

The disengagement torque may be precisely defined as a result of thedesign of the clutch device located between the two element parts whichare separate from one another. When this defined disengagement torque isexceeded, the clutch device is disengaged and the second element parthaving the engagement means is available in a freely rotatable mannerfor pretensioning the fastening element, which is already anchored inthe substrate. The disengagement torque of the clutch device is set insuch a way that during the drilling process the two element parts remainin a coupled state for transmitting drilling torque.

The adapter has a small number of parts, which are connected to oneanother. The two element parts are easily manufacturable and may have arobust design, which represents an important economic advantage inparticular for a mass-produced product, as is the case for the adapteraccording to the present invention.

At the start of the drilling process, the adapter does not have to bescrewed in until it appears at the free end of the shank. Duringoperation of the drill, the adapter rotates until it contacts the screwstop on the second, free end of the shank. The shank is then drilledinto the substrate, via the adapter, with the aid of the drill until theintended drilling depth is reached. The base section of the adapterprovides a screw stop for the adapter.

For a fastening element in the form of a chemical shear connector, theshank has a hollow cylindrical design, the interior space formed by theshank being used to conduct the curable compound or to accommodate acurable compound in the shank. The base section on the first elementpart of the adapter may be used as a retaining device for the compound,situated in the shank, to be pressed out. The compound to be pressed outis packaged in a film bag, for example, and is situated in a receptacle,for example in an interior tube, in the shank. This is particularlyadvantageous for overhead applications, since due to the base sectionthe compound to be pressed out is not able to slide out of the hollowcylindrical shank. A preferably central opening is advantageouslyprovided in the base section which allows a pressing mechanism to beinserted in order to apply the compound to be pressed out, situated inthe shank, without having to remove the adapter from the free end of theshank for this work step.

The shank, for example an anchor tube, may be provided as piece goodswhich are cut to the required or desired length on site. Because thedrill bit head is mounted only on the shank, this preassembly step mayalso be carried out on site. To improve the extraction parameters offastening elements such as rock anchors, the shank is often providedwith exterior profiling along its entire length. The inner thread of theadapter is preferably matched to the outer thread, which is provided asprofiling. If the shank does not have an outer thread on its exterior, asuitable thread may be provided, for example cut, on site on the freeend of the shank for connecting the adapter. Generous tolerances may bepresent between the inner thread on the adapter and the outer thread onthe shank without greatly limiting the functioning of the connection ofthese two parts. As a result, for a shank cut to size on site, deburringof the cut surfaces may usually be dispensed with.

The quick-engagement device advantageously has a wrench connection. Abihexagonal or polygonal design, for example, is used as the wrenchconnection, thus minimizing the angle of twist for finding thegeometries for connecting the rotary tool receptacle of the drill to thefastening element. In addition, a tool may be placed on the wrenchconnection, if necessary, for screwing and unscrewing the adapter on theshank.

The clutch device preferably includes an axially extending stop surfacesituated on the first element part and an axially extending counterstopsurface situated on the second element part for transmitting thedrilling torque. In the case of a clutch device having elements whichshear or break off, a disengagement torque of the clutch device may beeasily defined via the size of the contact surfaces of the stop surfaceand counterstop surface which may be brought into contact with oneanother.

For a drilling process having a reverse rotation of the drive of thedrill, first the fastening element is drilled into the substrate, thestop surface and the counterstop surface being in mutual contact fortransmission of the drilling torque. After the anchoring depth isreached and the curable compound is at least partially cured, the drillis started up again, the rotational direction of the drive beingreversed with respect to the drilling rotational direction. The secondelement part is then freely rotatable, and in order to pretension thefastening element which is already anchored in the substrate, may thenbe moved by the drill in the direction of the substrate or in thedirection of the drill bit head, for example, until contacting an anchorplate provided on the substrate.

On one of the element parts the clutch device preferably includes atleast one cam which projects beyond a free edge, and at least one recessprovided on the free edge of the other element part, the at least onecam engaging in the at least one recess for transmission of torque. Fortransmission of drilling torque, the side face of the cam extending inthe rotational direction comes into contact with the corresponding sideface of the recess. When the fastening element already anchored in thesubstrate is braced, the cam, for example, slides out of the recess onthe other element part, and the element part having the engagement meansmay be moved along the shank in a freely rotatable manner.

Alternatively, the at least one cam breaks off when the disengagementtorque of the clutch device is exceeded, so that the element part havingthe engagement means may be moved along the shank in a freely rotatablemanner. The height of the at least one cam of the corresponding elementpart which projects beyond the free edge of the corresponding free edgeis selected in such a way that the center of gravity of the sheared orbroken-off cam element is situated within the recess. This ensures thatthe at least one sheared or broken-off cam element remains within therecess after the clutch device is disengaged.

At least one of the side walls of the at least one recess preferablyextends at an angle relative to the center of rotation of thecorresponding element part. The side wall extending at an angle relativeto the rotation, i.e., obliquely or transversely with respect to aradius, may be used, depending on the orientation of the inclination, onthe one hand as a securing surface for retaining a sheared or broken-offcam element, or on the other hand as a guide surface to facilitatesliding of the at least one cam from the at least one recess when thedisengagement torque of the clutch device is exceeded.

If the fastening element is set in a reverse rotation process, the sidewall of the recess lying or extending in the drilling directionadvantageously has an inclination which extends axially and essentiallyin the direction of the center of rotation, so that at this location theentire contact surface is available for transmitting the drillingtorque. The side wall of the recess located opposite and trailing theside wall situated in the drilling direction advantageously extends atan angle relative to the center of rotation of the corresponding elementpart, the angle relative to the center of rotation being selectedaccording to the requirements, for example for retaining a section ofthe at least one cam, or to facilitate sliding of the at least one camfrom the at least one recess.

Retaining means are preferably provided in the region of the clutchdevice which advantageously hold the two element parts together in theinstalled state of the adapter. This allows the adapter to be situatedas a unit on the free end of the shank, so that the two element parts donot have to be separately assembled on the free end of the shank. Theretaining element also ensures that, for example, a sheared orbroken-off cam element remains in the recess. The retaining means areadvantageously flexible, and also advantageously produce a radiallyinward pretension on the corresponding edges of the element parts, thusensuring simple installation. The retaining means are made of plastic ormetal, and are also advantageously designed as a closed ring.Alternatively, the retaining element is made of multiple interconnectedtab elements which join the two element parts together in places intheir contact region.

A radially circumferential depression is preferably provided in eachcase on the free edges of the element parts, and the retaining means aresituated in this depression, thus ensuring simple installation of theadapter.

The first element part is preferably secured on the second end of theshank in a rotationally fixed manner, thus preventing the first elementpart having the base section from accidentally coming loose during thesetting process for the fastening element. In particular for a settingprocess for the fastening element using reverse rotation of the drilldrive, the first element part which is secured on the second end of theshank in a rotationally fixed manner ensures simple anchoring andpretensioning of the fastening element. During the drilling process, thesecond element part having the engagement means is moved in thedirection of the free, second end of the shank, the first element partwhich is secured on the second end of the shank in a rotationally fixedmanner preventing the adapter from twisting off from the shank of thefastening element. In the subsequent reversed rotation, the secondelement part is moved away from the first element part which is securedin a rotationally fixed manner. The type of securing of the firstelement part is advantageously selected in such a way that the firstelement part is able to sufficiently absorb the forces which arise inthe drilling process.

The first element part is preferably secured on the second end of theshank in a positive-fit manner, which ensures that the first elementpart is adequately secured on the second end of the shank. Axiallyextending bore holes are advantageously provided in the first elementpart and the shank of the fastening element, which together form areceptacle for a connecting pin. The bore holes advantageously extendstarting from the base section of the first element part, and areexternally accessible for installation of the connecting pin.Alternatively, the section of the bore hole extends, at least in thefirst element part, starting from the end facing the second elementpart, in the direction of the base section of the first element part, itbeing possible to similarly insert the connecting pin from this end forsecuring the first element part on the second end of the shank in arotationally fixed manner. In a further alternative, a bore holeoriented radially inward is provided in the first element part, and aconnecting pin which engages in the end region of the second end of theshank is inserted into the bore hole.

Further options for securing the first element part on the second end ofthe shank in a rotationally fixed manner include providing an adhesiveor a clamping connection, for example by deforming the correspondingcontact surfaces between the first element part and the end region onthe second end of the shank. A further option includes, but is notlimited to, shrink-fitting the first element part on the second end ofthe shank.

The adapter is advantageously manufactured in a casting process.Subsequent machining of the cast adapter may be dispensed with onaccount of the allowable tolerances. Besides this economicalmanufacturing method, the adapter may also be manufactured in acasting/milling process, for example.

The present invention is explained in greater detail below withreference to exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a self-drilling, chemically anchorable rock anchor in aside view;

FIG. 2 shows a first exemplary embodiment of an adapter in an enlargedside view;

FIG. 3 shows the first element part of the adapter according to FIG. 2in a partial section;

FIG. 4 shows the adapter according to FIG. 2 in a longitudinal section;

FIG. 5 shows a second exemplary embodiment of an adapter in a side view;

FIG. 6 shows the adapter in a first longitudinal section according toline VI-VI in FIG. 5;

FIG. 7 shows the adapter in a second longitudinal section offset by 90°relative to the first longitudinal section, according to line VII-VII inFIG. 5; and

FIG. 8 shows the adapter in a cross section according to line VIII-VIIIin FIG. 5.

Identical parts are basically provided with the same reference numeralsin the figures.

DETAILED DESCRIPTION

Chemically anchorable fastening element 11 illustrated in FIG. 1, in theform of a rock anchor, has a hollow cylindrical shank 12 or anchor tubewhich is provided with a drill bit head 16 on a first end 13, and whichhas a second, free end 14 situated opposite first end 13. Shank 12 isprovided with a threadlike outer profile 15 in places at an end regionon second end 14. Threadlike outer profile 15 advantageously extendsover the entire longitudinal extension of shank 12. A curable compound17 packaged in a film bag is provided in the receptacle formed by hollowcylindrical shank 12.

An adapter 21, illustrated in detail in FIGS. 2 through 4, is providedon second, free end 14 of shank 12. Adapter 21 is formed by a firstelement part 22 and a second element part 32 which are detachablyconnected to one another via a clutch device 41.

First element part 22 has a base section 23 with a central opening 24,and has a first hollow cylindrical connecting sleeve section 25 whichprojects from base section 23 on one side of base section 23. A sealingelement 27 is situated in opening 24 in base section 23. The interior offirst hollow cylindrical connecting sleeve section 25 is provided inplaces with a threadlike inner profile 26 which may screwed ontothreadlike outer profile 15 at the end region on second end 14 of shank12.

Two bore holes 28 situated opposite each other extend, starting frombase section 23, and in places each bore hole merges into a groove 18 onsecond, free end 14 of shank 12. Two connecting pins 29 may be insertedinto these bore holes 28, thus allowing first element part 22 to besecured on second end 14 of shank 12 in a rotationally fixed andpositive-fit manner.

Second element part 32 has a hollow cylindrical design, and on one end33 has a radially outwardly projecting collar 34 which adjoins exteriorengagement means or device 35, having a polygonal design, for a rotarytool receptacle of a drill which is to be used. The section adjoiningengagement means 35 forms second hollow cylindrical connecting sleevesection 36. The interior of second element part 32 is provided in placeswith a threadlike inner profile 37 which may be screwed onto threadlikeouter profile 15 of shank 12.

Second hollow cylindrical connecting sleeve section 36 also has anexterior threadlike outer profile 15 in places for mounting fasteningmeans, such as a lock nut. Since adapter 21 for the most part remains onshank 12 even after fastening element 11 is set, adapter 21 may be used,for example, for fixing a pad to the wall of the cavity to be secured.Such pads are, for example, reinforcing mats or mesh pads made of metalor plastic which provide protection from unsecured falling rock. Thesepads are advantageously situated in an overlapping manner in the regionof the set fastening element 11. As the result of providing fasteningmeans on adapter 21, in a first step a first pad may be secured as suchto adapter 21. A second pad is then placed over adapter 21 and issecured using the same or other fastening means.

For transmitting the drilling torque, clutch device 41, which detachablyconnects first element part 22 and second element part 32 to oneanother, includes two axially extending stop surfaces 42 situatedopposite each other on first element part 22, and two axially extendingcounterstop surfaces 46 similarly situated with respect to one anotheron second element part 32. The free end of first hollow cylindricalconnecting sleeve section 25 of first element part 22 extends in aspiral manner between stop surfaces 42, the pitch being designed to begreater than the pitch of threadlike outer profile 15 of shank 12. Thefree end of second hollow cylindrical connecting sleeve section 36 ofsecond element part 32 likewise extends in a spiral manner betweencounterstop surfaces 46, the pitch being designed to be greater than thepitch of threadlike outer profile 15 of shank 12.

After adapter 21 is placed on free end 14 of shank 12, a drill is usedto set fastening element 11 in rotation in drilling direction 49 viaadapter 21. After the intended drilling depth is reached, the drill isshut off and curable compound 17 is pressed out, for example with theaid of a pressing device inserted through opening 24 in base section 23of first element part 22. When curable compound 17 reaches a specifieddegree of hardness, the drill is started up again, this time a rotationbeing exerted on adapter 21 in bracing direction 50, in the oppositedirection of drilling direction 49. Second element part 32 is moved in afreely rotatable manner in the direction of drill bit head 16, alongthreadlike outer profile 15 of shank 12, until fastening element 11 isbraced. Due to the spiral design of the free ends of first connectingsleeve section 25 as well as second connecting sleeve section 36,counterstop surfaces 46 are able to slide past stop surfaces 42 of firstelement part 22, which is on free end 14 of shank 12 in a rotationallyfixed manner, when element part 32 is axially displaced.

Adapter 51 illustrated in FIGS. 5 through 8 differs from previouslydescribed adapter 21 essentially in the design of clutch device 71 whichdetachably connects first element part 52 to second element part 62.First element part 52 is advantageously secured on the free end of theshank of the fastening element in a rotationally fixed manner. Clutchdevice 71 includes two cams 76 situated opposite each other whichproject beyond free edge 63 of second connecting sleeve section 66 ofsecond element part 62. Clutch device 71 also includes recesses 72,provided on free edge 53 of first connecting sleeve section 55 of firstelement part 52, corresponding to the orientation of cams 76; fortransmitting torque, cams 76 engage in the recesses.

Also provided on free edge 63 of second connecting sleeve section 66 ofsecond element part 62 are two spacing cams 64 situated opposite eachother, which in the installed state of adapter 51 lie against free edge53 of first connecting sleeve section 55 of first element part 52.Spacing cams 64 prevent free edges 53 and 63 from making surface contactwith one another, thus preventing adhesion between these free edges andtherefore preventing the free edges from influencing the disengagementtorque of clutch device 71.

Leading side wall 73 of recesses 72, which is situated in rotarydrilling direction 78, essentially extends in the direction of center ofrotation 56 of first element part 52. Trailing side wall 74 of recesses72, which is situated in bracing rotary direction 79, extends at anangle relative to center of rotation 56 of first element part 52, theinclination of these side walls 74 being oriented to retain a broken-offcam section in recess 72.

In the region of clutch device 71, first element part 52 as well assecond element part 62 are provided with a radially circumferentialdepression 81 in which flexible retaining means 82 designed as acircumferentially closed ring are provided.

1. An adapter for a self-drilling, chemically anchorable fasteningelement comprising: a shank with a first end, a drill bit head beingprovided on the first end, and with a second, free end, the second endof the shank being provided, at least in part, with a threaded outerprofile, an adapter placable on the second, free end of the shank andhaving an external engagement device on one adapter end for a rotarytool receptacle of a drill to be used, a base section being provided onthe other adapter end at a distance from the engagement device, and ahollow cylindrical connecting sleeve section connecting the base sectionand the engagement device, at least the connecting sleeve section havinga threadlike inner profile, at least in part, corresponding to thethreaded outer profile on the shank, the adapter being formed by a firstelement part and a second element part detachably connected to oneanother via a clutch device.
 2. The adapter as recited in claim 1wherein the clutch device includes an axially extending stop surfacesituated on the first element part and an axially extending counterstopsurface situated on the second element part for transmitting thedrilling torque.
 3. The adapter as recited in claim 1 wherein the clutchdevice on one of the first and second element parts includes at leastone cam projecting beyond a free edge, and at least one recess providedon the free edge of the other of the first and second element parts, theat least one cam engaging in the at least one recess for transmission oftorque.
 4. The adapter as recited in claim 3 wherein at least one of theside walls of the at least one recess extends at an angle relative to acenter of rotation of the corresponding first or second element part. 5.The adapter as recited in claim 1 wherein a retainer is provided in theregion of the clutch device.
 6. The adapter as recited in claim 5wherein a radially circumferential depression is provided in each caseon free edges of the first and second element parts, the retainer beingsituated in the depression.
 7. The adapter as recited in claim 1 whereinthe first element part is secured on the second end of the shank in arotationally fixed manner.
 8. The adapter as recited in claim 7 whereinthe first element part is secured on the second end of the shank in apositive-fit manner.